Ammonium-nitrate explosive and process of making it



Patented Mar. 4, 1930 WALTER 0. SNELLING, 0F ALLENTOWN, AND JOSEPH A. WYLER, 0 SOUTH? WHITE- HALL TOWNSHIP, LEHIGH COUNTY, PENNSYLVANIA, ASSIGNORS T0 TROJAN POW- DER COMPANY, OF NEW YURK, N. Y., A CORPORATION OF NEW YORK AMMONIUM-NITRATE EXPLOSIVE AND PROCESS OF MAKING IT We Drawing.

()ur invention relates to improvements in the manufacture of ammonium nitrate explo sives, and more particularly relates to a new and useful process for obtaining ammonium nitrate of high sensitiveness and great explosive strength, the invention also extending to explosive products whose preparation involves the process which we have invented.

Ammonium nitrate has long been used as a constituent of explosives. Ammonium nitrate, however, is of such low sensitiveness that it is not capable of use alone as an explosive, and accordingly has always been mixed with a considerable proportion of sensitizing materials. Many sensitizing materials have been used with ammonium nitrate in the preparation of commercial explosives, and one of the most successful of the latter is known as amatol, in which trinitrotoluene is employed as the sensitizing material. The amount of trinitrotoluene employed in the manufacture of amatol usually varies from 20% to 60% of the entire mixture, and amatols containing less than 5% to 10% of tri nitrotoluene are relatively insensitive and are not suitable for use as commercial ex plosives unless in addition to the trinitrotoluene there is also present some other detonating or sensitizing ingredient. In the manufacture of amatol, the mixture of the trinitrotoluene with the ammonium nitrate is a purely mechanical one, involving, even when heat is employed in the mixing, no appreciable chemical reaction between the two materials.

-We have discovered that by heating ammonium nitrate and trinitrotoluene together in the presence of certain other materials which are capable of reacting with them and of facilitating their reaction, we can obtain a new product quite dissimilar to the mechanical mixtures of ammonium nitrate and trinitrotoluene hitherto prepared, the new prodnot being extremely sensitive to detonatlon even when containing as little as 1% of trinitrotoluene.

As an example of one method which we may employ in the preparation of our new sensitized ammonium nitrate, we may take ten parts by weight of an alcohol, such as de- Application filed October 14:, 1922. Serial No. 594,584.

natured alcohol or methyl alcohol, ten parts by weight of water, ten parts by weight of metallic lead, one and one-half parts by Weight of trinitrotoluene, and sixty-eight and one-half parts of ammonium nitrate, these materials being heated gradually to 100 centigrade, and the mixture being stirred meanwhile. The lead employed is preferably present as lead turnings or sheet lead ofiering considerable surface. The temperature of the mixture may now be increased to 110 centigrade or even as high as 125 centigrade, the temperature of 115 Centigrade being preferred, and there follows a chemical reaction with a darkening in color of the whole mass, the reaction mixture changing from a light criaam color to a dark brown or almost black co or.

Although the reaction for the main part occurs within a relatively short time, we prefer to maintain the temperature at from 110 centigrade to 125 centigrade for several hours, since by heating for a longer time than is required for the reaction, the excess of water and alcohol evaporates, and by stirring the remaining material, we obtain our sensitized ammonium nitrate as a dark brown crystalline mass. Not all ofthe lead added to the above mixture is present in combined form in the finished product, a certain amount of the lead dissolving and forming a chemical compound, while the excess of lead remains in undissolved condition as metallic lead at the end of the heatin period. The excess of lead present as meta lic lead at the end of the reaction period may conveniently be removed and used again in the preparation of the next succeeding batch. As a convenient method of recovering the metallic lead, the latter may be suspended in the mixing kettle as sheet lead or as lead turnings held in a suitable basket or bag lu the reaction vessel.

It will, of course, be evident, however, that instead of employin metallic lead, we may under suitable conditions employ a compound of lead such as lead nitrate, litharge or other soluble or insoluble salt of lead. We prefer,

however, to employ metallic lead as described,

since in this case the proper amount of lead required for reaction dissolves, and any excess of lead may be readily removed at the end of the reaction period, and will not be present in the final mix as an inert or contaminating impurity.

Although it is preferred to bring about the reaction between the trinitrotoluene, ammonium nitrate and lead at a temperature in excess of 100 centigrade, we do not wish to be limited to the use of temperatures in excess of 100 centigrade. lVe have found that even at room temperatures, the reaction goes on very slowly, and that after several days the characteristic darkening in color occurs to some extent. Under these conditions, however, the reaction is far too slow to be of commercial significance. At higher temperatures, the reaction goes on much more rapidly until at 100 centigrade and particularly at ll0 to 115 centigrade it becomes'sufliciently rapid to form a desirable method of making our new sensitizing compound. It will be understood, however, that lower temperatures are capable under favorable conditions of yielding the same products by the use of a considerably longer period of time of preparation of the bodies.

Although the proportions which we have described represent the preferred proportions, our invention is not limited to the use of the materials described or to the proportions suggested. Although the use of an alcohol for example is desirable, it is not essential, but its use assists in shortening the time required to bring about the reaction between the trinitrotoluene and the ammonium nitrate. Where, therefore, speedy preparation of the material is desirable, we prefer to use alcohol, but for the ordinary commercial preparation of our new sensitized ammonium nitrate, we prefer not to use alcohol but to heat our reaction mixture to gether for several hours at a temperature of about 115 to 120 centigrade'. Otlier alcohols or other solvents for nitro bodies may be used instead of alcohol. Also instead of trinitrotoluene We may use other organic nitro bodies, but the reaction occurs most easily with the trinitro and dinitrotoluenes, and we prefer ,to use these bodies.

It is not known whether the trinitrotoluene and the lead react directly in producing our new sensitizing material or whether the trinitrotoluene is first reduced by the action of the metallic lead in the presence of ammonium nitrate to form some other body which reacts. It is known, however, that by proceeding as herein described, we are able 0 to obtain ammonium nitrate of high explosive strength. In view of the fact that in preparing our compound a chemical reaction occurs with evolution of gases and with a very marked darkening of the .color of the ammonium nitrate, it is probable that the trinitrotgluene is chemically combined with the reaction product of ammonium nitrate and lead and probably with the formation of some new compound which has very marked tinctorial properties, since as little formed in small amounts, and that the main product which we obtain by the method which we use consists of ammonium nitrate containing small traces of this new chemical body. The effect of even these small traces of the new chemical compound, however, is to cause a very marked sensitization of the entire mixture, and by following the process which is herein described, it is possibleto make a material containing one percent or less of trinitrotoluene which, when confined, will explode readily with an ordinary commercial detonating cap.

WVe have obtained successful results with ammonium nitrate containing as little as onetenth of one percent of lead and as little as two-tenths of one percent of trinitrotoluene. We prefer to use at least one percent of trinitrotoluene and one percent of lead, and we find that two parts of our new chemical compound containing lead is sufficient to sensitize ninety-eight parts of ammonium nitrate, yielding a product of high sensitiveness, When we employ our sensitized ammonium nitrate alone as an'explosive, we prefer to have from one percent to three percent of our chemically combined trinitrotoluene present in the mixture. Under these 1 conditions, the sensitized ammonium nitrate may be cartridged and used the same as any other explosive.

It is, of course, possible that the action of the lead is in part catalytic, although we find th'atthe'lead is actually present in chemically combined condition in our finished sensitized product. We find that the amount of surface of lead exposed has an effect in increas' ing the rapidity of the reaction, our finished product bei made more rapidly when the lead is a'dde as a fine powder than when present in large lumps or as sheet lead.

In one form of our invention, we mix together twenty parts of water, one part of triture in the reaction vessel may be crystallized or gently evaporated to dryness, yielding sensitized ammonium nitrate of high explosive strength.

Ammonium nitrate containing from onehalf of one percent up to three percent of trinitrotoluene in chemically combined condition is independently explosive and may, as previously stated, he used alone in cartridges or shells as an explosive. Or it maybe mixed with other materials as a constituent of explosive mixture. We prefer, however, to employ ammonium nitrate containing less than one percent of chemically combined trinitrotoluene as a constituent of other explosive mixtures made by adding suitable detonating, combustible and oxidizing ingredients.

The following is an example of such a mixture:

Per cent Nitrostarch 10 Ammonium nitrate containing .8% trinitrotoluene reaction product 79 Sodium nitrate 7 Aluminum 3 Zinc oxide 1' r We do not wish to confine ourselves to the above mlxture, however, since instead of nitrostareh, we may use any other det0nat-' our invention except as indicated in the appended claims. We claim: 1. The process which comprises heating together a mixture containing ammonium nitrate, water, lead, and nitrated toluene at a temperature in excess of 100 C. until a .chemical reaction occurs characterized by a pronounced darkening of the mixture. 2. The process of sensitizing ammonium nitrate, which consists in chemically reacting lead, trinitrotoluene and ammonium nitrate in the presence of' an excess of ammonium nitrate.

3. The process of sensitizing ammonium mitrate, which comprises treating the latter with a mixture of lead and nitrated toluene.

4. An explosive comprising nitrostarch and the herein described reaction product of ammonium nitrate, lead, and trinitrotoluene.

5. As a new composition of matter, ammonium nitrate sensitized by the product resulting from the reaction of ammonium nitrate, trinitrotoluene and lead.

6. As a new composition of matter, ammonium nitrate of high explosive sensitiveness containing a chemical reaction product of ammonium nitrate, lead and trinitrotoluene.

WALTER O. SNELLING." JOSEPH A. WYLER. 

